Variable area nozzle for power plants



Aug. 7, 1951 N. 0. PRICE VARIABLE AREA NOZZLE FOR POWER PLANTS 2 Sheets-Sheet 1 Original Filed March 6, 1942 INVENTOR NATHAN C. PRICE Agent Aug. 7, 1951 N. c. PRICE VARIABLE AREA NOZZLE FOR POWER PLANTS 2 Sheets-Sheet 2 Original Filed March 6, 1942 INVENTOR NATHAN 0. PRICE Agent Patented. Aug. 7, i951 g UNITED STATES- PATENT ornce vimm msglggz ia Foa rowan Nathan C. Price, Los Angeles, Calif., assignor to Lockheed Aircraft Corporation, Burbank, Calif.

Original application March 6, 1942, Serial No.

433,599, now Patent No. 2,540,991, dated February 6, 1951. Divided and this application March 14, 1947, Serial No. 734,649

1 19 Claims.

This invention relates to reactiv propulsion powerplants and has more particular reference to nozzles for this type of powerplant. The present invention is primarily intended for embodiment in internal combustion reaction type.

a gas turbine receiving the air and gases of combustion from the chamber, and. serving to drive the compressors and a nozzle for discharging the turbine exhaust in the form of a reactive propulsive jet. The speed of operation'of the turbine and, therefore, of the compressors, is dependent to a large degree upon the back pressure imposed on the turbine by the nozzle. Accordingly, variatiom in the effective area of the nozzle govern the speed of operation of the gas turbine and compressors. If provision is made for the injection of supplemental fuel into a supplemental combustion chamber, the temperature of the gases is increased and there is an increase in the volumetric flow through the nozzle which imposesa greater back pressure on the turbine. Variations in the pressurealtitude and ambient air temperatures likewise tend to vary the nozzle pressures and temperatures and the back pressure on the turbine.

It is an object of this invention to provide a powerplant of the class referred to incorporating an efficient nozzle for discharging the combustion gases and compressed air in the form of a high velocity reactive propulsion jet and incorporating means for varying the effective cross-sectional area of the nozzle to govern the speed of operation of the gas turbine and therefore control or affect the operation of the powerplant as a whole. The nozzle mechanism of the invention serves to vary the effective area of the nozzle passage and thereby control the back pressure on the turbine to compensate for variations in altitude pressures, ambient air temperatures and nozzle temperatures.

It is another object of the invention to provide a nozzle mechanism for gas reaction powerplants embodying simple effective means for antomatically varying the effective area of the nozzle passage. The invention provides a throat member movable axially toward and away from the partially restricted throat of the nozzle passage to alter the cross-sectional area of the nozzle while maintaining an efficient reactive jet effect.

A further object of the invention is to provide a nozzle means of the character referred tohaving a cylinder and piston device for moving the throat member in response to variations in the pressure in the supplemental combustion chamber and nozzle.

A still further object of the invention is to provide a nozzle construction of the class referred to wherein the cylinder and piston mechanism for moving the throat member is automatically controlled by a speed governor driven by the tur bine and therefore reflecting turbine speed and compressor speed. Provision is made for manually setting or adjusting the speed governor so that the throat member may be=made to assume any selected position for given powerplant operating conditions.

Other objects and features of the invention will become apparent from the following detailed description of a typical preferred form of the invention, throughout which reference will be made to the accompanying drawings, wherein:

Figure 1 is a side elevation of a powerplant embodying a nozzle means of the invention, with the upper portion of the powerplant appearing in longitudinal cross-section and with the nozzle mechanism associated with a gas turbine reactive propulsion powerplant of the class disclosed in my co-pending application referred to above. The general structure of the powerplant is disclosed herein because the nozzle mechanism is operatively related to its various components. However, the specific construction of the powerplant is omitted as not essential to an undertaking of the present invention.

Referring now to Figure l, the powerplant comprises generally, first and second stage compressors I and II, a combustion chamber I2, a gas turbine I3, and a nozzle means I4.

The powerplant is adapted for use in high speed, high altitude aircraft and is designed to handle a substantial volumetric air flow. The first stage compressor I0 is of the axial flow type and is provided at its forward end with a tubular spigot I5 for the reception of rammed air. The Spigot I5 faces forwardly with relation to the direction of flight of the aircraft and is of substantially the same diameter as the housing I6 of the compressor. The compressor I0 includes a wheel or rotor I1 of forwardly diminishing diameter supported concentrically in the housing l6 for rotation therein. The rotor I1 carries axially spaced rows of circumferentially spaced blades IB and the housing carries a plurality of rows of diffuser vanes l9 arranged to extend intermediate the rows of impeller blades I8. The rear or exhaust end of the compressorterminates in a double scroll outlet housing having a pair of outlet spigots 2| and 22 which communicate with intercoolers 23.

The second stage compressor II shown in Fig-- ure 1 is of the multi-stage radial flow type and comprises three stages 24, 25 and 26 of centrifugal compression arranged in tandem relation. The first stage centrifugal compressor 24 is at the rear of the scroll 20 and has two spigots 21 and 28 receiving the first stage compressed air from the intercoolers 23. An annular exhaust duct 29 of the compressor 24 directs the compressed air through a liquid fed intercooler 30 which in turn directs the air to the inlet 3| of the second stage centrifugal compressor 25. The second'and third stage centrifugal compressors are directly connected in tandem and the air from the final stage compressor passes through diffuser vanes}! to the combustion chamber I2.

The combustion chamber I2 comprises a housing 33 and an annular shroud 34 which together define an annular space leading from the exhaust of the final stage compressor 26 to the nozzle ring 46 of the turbine. The housing and shroud are shaped to have an annular series of interconnected parallel pockets which carry burner tubes 35. Fuel spray nozzles 36 extend into the tubes and are supplied with compressed air and fuel by annular supply manifolds 31. Electrical resistance glow plugs 38 serve to ignite the fuel-air mixture formed in and flowing through the combustion chamber.

The gas turbine I3 includes a cylindrical housing 40 and a tapered rotor 4| coaxially positioned in the housing. The rotor 4| is fixed to a shaft 42 rotatably supported by one or more bearings 43. Impeller blades 44 on the rotor 4| operate between rows of stator blades 45 on the housing 40. The above mentioned nozzle ring 46 discharges the gases of combustion and excess air from the combustion chamber I2 into the expansion zone of the turbine.

Provision is made for the injection of supplemental fuel from the apex of the turbine 4|. A cap at the apex of the rotor has divergent orifices 41 supplied with fuel by the hollow turbine shaft 42. Supplemental fuel injected at the orifices 41 greatly increases the thrust of the powerplant, the supplemental fuel burning in the excess air leaving the turbine and entering the propulsive nozzle.

Cooling air from the exhaust passage of the final stage compressor 26 flows through the interior of the turbine rotor 4| to adjacent its a p ex and then flows back or forwardly around a baffle 48 as indicated by the arrows in Figure l to discharge into the expansion zone of the turbine at the forward end of its rotor. This freeor unconsumed air is continuously circulated through the rotor 4| to cool the same and is mixed with the gases of combustion and unconsurned air leaving the combustion chamber I2. A secondary combustion chamber 49 extends rearwardly from the turbine housing. The chamber 49 is rearwardly convergent and carries an internal annular baflie 50. The baffle 50 is arranged in the entrance of the secondary combustion chamber to surround or oppose the supplemental fuel orifices Power is transmitted from the turbine I3 to the compressors I0 and II by gear transmissions. A beveled gear 5| is fixed on the forward end of the rotor shaft 42 and meshes with beveled pinions 52, each splined to a radial auxiliary shaft 53. The radial flow compressor I! has a shaft 54 and a gear 55 is fixed on the shai to mesh with the inions 52. Thus the compressor shaft 54 is driven by the turbine I3 in a counter-rotation direction. A somewhat similar gear transmission 56 is provided between the shaft 54 of the second stage compressor II and the rotor of the first stage compressor III to drive the latter at the selected speed in relation to the second stage compressor. The details of this gear mechanism are omitted as not essential to an understanding of the present invention.

The nozzle means I4 of the invention includes a nozzle N continuing rearwardly from the secondary combustion chamber 49 and designed to produce an effective reactive propulsive jet of the combustion gases and air exhausting from the turbine I3 and secondary combustion chamber. The nozzle N may be a continuous tubular extension of the chamber 49 and is preferably lined with a refractory lining 51 of carborundum or the like. This lining 51 continues forwardly to cover the inner wall of the chamber 49. In the construction illustrated the nozzle N has a Venturi shaped passage 58 clearly illustrated in Figures 1 and 2.

The nozzle means further includes an inner longitudinally movable annular throat member 59 arranged at the upstream side of the throat restriction of the nozzle passage 58. The member 59 has a cylindrically curved external surfaceand an airfoil shaped internal surface defining a Venturi-like passage. As illustrated in the drawings, the throat member 59 is proportioned so as to be spaced from the interal wall of the nozzle N leaving an annular passage 60. The throat member 59 is supported by a plurality of parallel axially extending rods 6|. Generally radial arms 62 extend between and connect the rods 6| and the forward end portion of the throat member 59. The rods 6| extend rearwardly to slidably pass through openings 63 in the lining 51 and enter an annular servo cylinder 64 in the wall of the nozzle N. The rear ends of the rods 6| are fixed to an annular piston 65 operating in the cylinder. A number of coil springs 66 is arranged under compression between the piston 65 and the forward wall of the cylinder 64 to urge the rods 6| and throat member 59 rearwardly.

The rods 6| just described have axial bores 61 which extend rearwardly through the piston 65. The forward ends of the openings or bores 61 communicate with the interior of the nozzle N and secondary combustion chamber 49 and the rear ends of the bores communicate with the or active end of the cylinder 64 and connected with the body of a bleed control valve by a tube 9|. The control valve Il may be located at any convenient place in the aircraft. The valve 10 includes a stem 1| adapted to cooperate with a beveled valve seat 12 which surrounds an atmospheric vent II. In accordance with the invention the valveis sensitive to powerplant speed,

that is to variations in the speed of the turbine i3 and compressors Ill and H. The valve stem H is operatively connected through suitable linkage with a speed governor II. The linkage may comprise a lever "connected with the valve stem ll a rod 18 pivotally connected with the lever and a bell crank ll connected with the rod I8 and operatively associated with the governor 14., The governor 14 is driven by one of the above'described auxiliary shafts 53 to operate in response to the speed of the turbine IS. The linkage just described is such that upon an increase in speed of the turbine I3 the governor It acts to increase the effective area of the bleed valve vent opening 13 and upon a decrease in turbine speed acts to reduce the effective area of the needle valve vent.

Manually operable means is provided to regulate or adjust the speed setting of the governor 14 with respect to the needle valve action. The lever I5 is pivotally supported on a threaded shaft 19 which can be manually adjusted by a shaft extension 80 provided with a hand wheel 8|. The movable annular throat member 59 is shaped so that its axial displacement resulting from pressure variations in the cylinder 64 changes the effective area of the nozzle passage while maintaining a high nozzle efllciency. The pressure in the cylinder 64 is varied or influenced by pres sure and temperature conditions in the powerplant and is modified by the governor controlled needle valve Ill.

During operation of the powerplant the pressure in the secondary combustion chamber 49 is transmitted through the ducts 61 of the rods ii to the cylinder 64 and acts on the piston 65 to urge the throat member 59 forwardly. This gas pressure compresses the springs 66 and urges the member 58 toward its forward position indicated by the broken line it where the nozzle N has a maximum effective cross-sectional area. The initial setting or adjustment of the speed governor II is obtained by the screw I9 remotely controlled by the shaft 80 and wheel 8! which may be located in the flight compartment for convenience of operation.

If the pressure in the secondary combustion chamber 49 increases above a correct value due to the introduction of supplemental fuel, for example, the turbine speed will tend to decrease due to the attendant back pressure and the resultant corresponding increase in pressure in the cylinder 54 then tends to move the annular throat member forwardly in the nozzle N to increase the effective area of the nozzle throat with an accompanying reduction of back pressure on the turbine, tending to correct the condition. If the pressure altitude of the aircraft varies the corresponding tendency upon the gas turbine speed by altered compressor load also reacts on the governor I4 and the accompanying actuation of the needle valve stem II is such as to'correspondingly open or close the effective area .of the nozzle throat. Accordingly, a substantially constant turbine speed is maintained when the pressure altitude is increased or decreased. The gas turbine carries whatever load is imposed on it by e the compressor system and the airplane auxiliaries. If the turbine produces a power excess the speed governor It acting through the above described nozzle mechanism will increase the back pressure on the turbine. If there is a reduction in turbine power the speed governor de creases the back pressure on the turbine by changing the position of the nozzle throat member 59. Accordingly the gas turbine and the directly connected compressor means are operated as constant speed devices. Consequently the efliciency of these units is particularly high un-- der all operating conditions and at all altitudes and the powerplant is stable under conditions of rapid change of load.

Having described only a typical form of the invention, I do not wish to be limited to the specific details herein set forth, but wish to reserve to myself any variations or modifications that may appear to those skilled in the .art and/or fall within the scope of the following claims.

I claim:

1. In a gas reaction propulsive unit, apparatus comprising in combination, a gas turbine, a nozzle communicating with the exhaust of said turbine and adapted to produce a propulsive jet of combustion gases, means responsive to the combined effect of the discharge pressure and the speed of said gas turbine to vary the effective cross-sectional area of the throat of said 'nozzle to regulate the back pressure on said turbine in such manner as to tend to maintain said gas turbine at a constant speed.

2. In a gas reaction propulsive unit, apparatus comprising in combination, a gas turbine, a nozzle communicating with the exhaust of said turbine and adapted to produce a propulsive jet of combustion gases, means responsive to the .speed of said gas turbine to vary the efiective crosssectional area of the throat of said nozzle to regulate the back pressure on said turbine in such manner as to tend to maintain said gas turbine at a constant speed.

3. In a gas reaction propulsive unit, apparatus comprising in combination, a gas turbine, a nozzle having a convergent-divergent passage communicating with the exhaust of said turbine adapted to produce a propulsive jet of combustion gases, an annular shaped airfoil sectioned throat member in said passage, said member being spaced from the wall of the passage to leave a flow path therebetween and being longitudinally movable to vary the effective cross-sectional area of the throat of said nozzle to regulate the back pressure on said turbine, means operstrictlon spaced between its ends, an annular shaped airfoil sectioned throat member coaxially positioned with respect to the nozzle opening at the upstream side of said restriction and adapted to be moved longitudinally along the nozzle axis toward and away from said restriction of said nozzle in a manner adapted to vary the effective cross-sectional area of the throat of said nozzle to regulate the back pressure on said turbine, said member being spaced from the inner wall of the nozzle to leave a flow path, means operable to move the throat member, and a governor driven by the turbine and operable to modify the operation of the first named means in accordance with the rotative speed of the turbine.

5. In a gas reaction propulsive unit, apparatus comprising in combination, a gas turbine, a nozzle communicating with the exhaust of said turbine and adapted to produce a propulsive jet of combustion gases, an annular shaped throat member coaxially positioned with respect to the nozzle opening and adapted to be moved longitudinally along the nozzle axis with respect to the section of maximum contraction of said nozzle in a manner adapted to vary the effective crosssectional area of the throat of said nozzle, and means responsive to the combined effect of the discharge pressure and the speed of said gas turbine to move the said throat member in such manner as to tend to maintain said gas turbine at a constant speed.

6. Apparatus according to claim in which the means to move the auxiliary throat member comprises a servo-cylinder, a piston in said cylinder adapted to take a position in said cylinder proportional to fluid pressure therein, means to transmit fluid pressure to said cylinder in proportion to the discharge pressure of said gas turbine, means to modify said fluid pressure on said piston in accordance with a function of the rotative speed of said turbine and a mechanical linkage movably coupling said piston and said annular throat member.

'7. In a gas reaction propulsive unit, apparatus comprising in combination, a gas turbine, a secondary combustion chamber in down stream relation to the turbine, means for introducing fuel into said chamber, a nozzle communicating with down stream side of said chamber and adapted to produce a propulsive jet of combustion gases, fluid pressure actuated means responsive to the discharge pressure of said turbine to vary the effective cross-sectional area of the throat of said nozzle to regulate the back pressure of said turbine in such a manner as to tend to maintain said gas turbine at a constant speed, and governor means responsive to the rotative speed of the turbine for modifying the action of saidfiuid pressure actuated means.

8. In a gas reaction propulsive unit, apparatus according to claim 1 in which the means to vary the effective cross-sectional area of the throat of the nozzle comprises, an annular shaped airfoil sectioned longitudinally movable throat member adapted to be moved along the nozzle axis with respect to the section of maximum contraction of said nozzle.

9. In a gas reaction propulsive unit, apparatus in accordance with claim 2 in which 'the means to vary the effective cross-sectional area of the throat of said nozzle comprises, an annular shaped airfoil sectioned longitudinally movable throat member adapted to be moved along the nozzle axis with respect to the section of maximum contraction of said nozzle.

10. In a gas reaction propulsive unit, apparatus comprising in combination, a gas turbine, a nozzle communicating with the the exhaust of said turbine and adapted to produce a propulsive jet of combustion gases, an annular shaped throat member coaxially positioned with respect to the nozzle opening and adapted to be moved longitudinally along the nozzle axis with respect to the section of maximum contraction of said nozzle in a manner adapted to vary the effective cross-sectional area of the throat of said nozzle, and means responsive to the speed of said gas turbine to move said throat member in such manner as to tend to maintain the gas turbine at a constant speed.

11. In a gas reaction propulsive unit, the combination of a gas turbine, a nozzle communicating with the exhaust of said turbine and adapted to produce a propulsive jet of combustion gases,

and means responsive to the speed of said turbine to vary the effective cross-sectional area of the throat of said nozzle.

12. Nozzle means for a reactive propulsion power plant having a gas turbine and a turbine exhaust passage, the nozzle means comprising a nozzle communicating with said passage, a throat member movable in the nozzle to vary the effective area of the nozzle, fluid pressure actuated means for moving the throat member, and means responsive to the speed of said turbine for modifying the action of said fluid pressure actuated means.

13. Nozzle means for a reactive propulsion power plant having a gas turbine and a turbine exhaust passage, the nozzle means comprising a nozzle communicating with said passage, a throat member movable in the nozzle to vary the effective area of the nozzle, fluid pressure actuated means for moving the throat member, means responsive to the speed of said turbine for modifying the action of said fluid pressure actuated means, and manually operable means for regulating the last named means.

14. Nozzle means for a reactive propulsion power plant having a gas turbine and a turbine exhaust passage, the nozzle means comprising a nozzle communicating with said passage, a throat member movable in the nozzle to vary the effective area of the nozzle, means for moving the throat member, and means responsive to the speed of said turbine for modifying the action of the means for moving the throat member.

15. In a reactive propulsion powerplant having a gas turbine and a turbine exhaust passage, the combination of a nozzle casing communicating with said exhaust and adapted to discharge the turbine exhaust gases in the form of a reactive jet, a throat member movable in the nozzle casing to vary the back pressure imposed by the nozzle, fluid pressure actuated means for moving the throat member comprising a cylinder and a piston, a conduit for conducting actuating fluid pressure to the cylinder of said means, a second conduit for conducting fluid pressure from said cylinder, valve means for one of said conduits operable to control the operation of said means, governor means responsive to the rotative speed of the turbine for operating said valve, and manually operable means for regulating the speed setting of the governor means with respect to said valve.

'16. In combination with a reactive propulsion powerplant having a gas turbine and a turbine exhaust passage, nozzle means for utilizingthe turbine exhaust gases to secure a propulsive effeet, said means comprising a tubular nozzle casing communicating with said passage. as throat member supp rted for axial movement in the nozzle casing to vary the back pressure imposed by the nozzle means, fluid pressure actuated means for moving the throat member including a cylinder and piston, means for supplying actuating fluid pressure to the cylinder of said means, and means responsive to the speed of the turbine for modifying the action of the fluid pressure actuated means.

17. Nozzle means for the exhaust passage of a reactive propulsion unit comprising a tubular nozzle communicating with said exhaust passage and having a throat restriction, a tubular throat member movable axially with respect to said restriction to vary the eil'ective cross-sectional area of the nozzle, and means for moving the throat member including an annular cylinder in the wall of the nozzle, a piston operable in the cylinder and connected with the throat member, a

conduit for sup lying actuating fluid pressure to the cylinder, 9. second conduit for conducting fluid pressure from the cylinder, and means for controlling one of said conduits.

18. Nozzle structure for the exhaust of a reactive gas propulsion unit comprising a tubular nozzle for communicating with the exhaust, a throat restriction in the nozzle adjacent the discharge end of the same, there being axialopenings passing through the wall of the restriction and having their forward ends open to the inte rior oi! the nozzle, a tubular throat member, through which the gases pass, and means for supporting the member for axial movement relative to the restriction including movable supportrodsspacedradiallviromthememberand slidably supported in said openings to extend into the interior of the nozzle, and arms extending radially tromthememberto therodsto connect 10 the same and spaced upstream from the restriction and from the do end of said member 19. Nozzle means for a reactive propulsion unit having an exhaust comprising a nomle communicating with exhaust of the unit, the nozzle including a nozzle wall, an axially movable throat member for varying the effective area of the nozzle, a cylinder and piston mechanism for moving the throat member including rods extending axially in said nozzle wall and projecting into the interior of the nozzle to support and move the throat member, said rods constituting the sole supports for the throat member, and means for conveying fluid pressure to the cylinder and piston mechanism to actuate the same.

NATHAN C. PRICE.

REFERENCES CITED The following references are of record'in the file of this patent:

UNITED s'ra'rns Pam-rs Number Name Date 607,548 Pinker-t July 19, 1898 658.586 Reiling Sept. 25, 1900 941,426 Loudon Nov. 30, 1909 1,493,157 Mlot May 6, 1924 1,750,417 McClellan et a1. Mar. 11, 1930 1,779,009 Negro Oct. 21, 1930 2,290,835 Lysholm Apr. 28, 1942 2,390,161 Mercier Dec. 4, 1945 2,402,363 Bradbury June 18, 1946 FOREIGN PATENTS Number Coimtry Date 848,225 France July 17, 1939 295,515 Germany July 30, 1917 310,926 Germany Feb. 8, 1919 483,888

, Germany Oct. 7, 1929 

